Screw-machine tool



' (No Model.) v

J. HARTNESS.

SCREW MAGHNB TOOL.

No. 424,979. Patented Apr. 8, 1890.

F II L' IIIIIIII l IIIIIIIIIIIIII I I I I I I I I I I I U I I I I I I l I I I I WITNESS@ i.

UNITED STATES PATENT QEEICE.

JAMES HARTNESS, AOF SPRNGFIELD, VERMONT.

SCREW-MACHINE TOOL.

SPECIFICATION forming part of Letters Patent No. 424,979, dated April 8, 1890. Application tiled October 2, 1889. Serial No. 325,816. (No model.)

To all whom it may concern:

Be it known that I, JAMES HARTNEss, a citizen of the United States, residing at Springiield, in the county of Vindsor and State of Vermont, have invented a new and useful Tool for Turret-Lathes, of which the following is a speciiication.

My invention relates to improvements in that kind of turningtools for use in the turret of turret-lathes, commonly called boX- cutters, and the objects of my invention are to obtain an accurate Working, cheap, and simply-constructed box-cutter for turning taper and symmetrical shapes. These objects I attain by the mechanism illustrated in the accompanying drawings, in which* Figure lis a plan; Fig 2 the side, and Fig. 3 the end, elevation of the box-cutter complete. Fig. 4 is a Side and end elevation of the former c in Figs. l, 2, and 3. Fig. 5 shows work before it is operated upon, Fig. 6 as turned by the herein-described invention, and Fig. 7 as finished by other tools.

The main part or body A of this invention (shown in Figs. l and 2) is provided with a round shank by which it is held in the turret. A flange bolted to the outside is sometimes used instead of said round shank.

A (shown dotted in Figs. l, and 3) are lugs to which cutter-holder B is secured by pointed screws y, said screws being adjusted to allow a free pivotal motion to the same, the cutter D being forced into the Work by former c and withdrawn by spring u, said spring keeping a constant bearing of adjusting screw ,e on former c.

Fig. 4 shows the shape of former used for making bolts, as shown by Fig. 7, and for other work this shape may be changed to a more or less taper or to an irregular pattern, as required. This former is preferably made of one piece, although it can for taper-work be made of several pieces, forming an adjustable former.

The gib w in Figs. l and 3 is used for holding the former c in position.

Pin c in Figs. l, 3, and i is used for holding the former c motionless as the box-cutter passes over the work-in other words, to keep the former in the same relative position to the Work during the entire cutting time of the movable cutter l). This causes the cutter holder B, Fig. 2, to .move on pivot-screws y, Fig. 2, and give substantially a radial travel toward center of work of the tool-point.

Bushing E in body A is used only on slender work requiring a support or back-rest, and in using it the entire length is not taper, but, as shown by Fig. 6, is left to be finished by other tools.

' The relative position of the pivotal point y, Fig. 3, to the cutter-point and the point of contact c of cutter-holder with former c gives great accuracy of work, for if the former is slightly inaccurate that inaccuracy is divided at the tool-point. The cutter-h0lderB is substantially a lever with a tool attached to the short end.

NVhen this box-cutter is used on turretlathes with a non-reversible power-feed7 it is necessary to run the lathe backward to make the feed travel from the shoulder or head toward the point, and for this reason I make the box-cutter left-handed and place the backrest bushing E back instead of front of cutter; but I do not confine my claims to this peculiar construction, for on other kinds of Work it is sometimes desirable to have the tool made right-handed-i. e., to cut with forward motion of lathe. On long and slender work requiring the back-rest it is necessary to turn the Work the size of bushing E. This may be accomplished by cutter D or by another tool; but when used on work that does not require the taper close to a shoulder a fixed tool is clamped in front of the back-rest and the movable cutter is placed back of the baclerest.

To operate this bozccutter on work, (shown by Fig. 7,) I prefer to proceed as follows after f the Work has been reduced to a cylindrical shape a trie larger than the largest part of the inished piece and closely fitting backrest E: First, by passing the tool over the Work, said work being motionless till the cutter reaches the head; second, by bringing a projection from the carriage or bed of the lathe into Contact with pin c on former c to prevent its traveling, then starting the lathe backward and gradually feeding the tool toward the point of the work until the required amount is turned, the former in the meantime having no travel relative to the Work. The former is then released and is pushed back into position for starting on the next piece of Work.

Another inode of operating is to leave a large cnd on the Work, as shown by Fig. G, turned to lit closely the hole in the body-piece A, this hole being one diameter its entire length, thus steadying the extreme end of the Work as the other part is shaped by the radially-traveling point of cutter D. \Vhen used in this Way, the cut is usually taken from the point toward the head, and the tool then precedes the back-rest, the former being pushed into instead of Withdrawn from the main body.

I am aware that in some instances taperturning machines for metal work have been constructed employing a former acting direct, with no advantage or leverage over the tool, as the taper attachment commonly used on engine-lathes, and that in Wood-working machines the tool is controlled by a former in a lathe commonly called the gage-lathe. The present claims do not cover such.

I claim as my invention- 1. In a box-cutter, the combination of a main body and a cutter-holder pivotally secured to said main body and caused io lnove on its pivots by former c, substantially as shown and described.

2. The combination, in a box-cutter, of a main body, a swivel cutter-holder, and a former sliding in said main body and acting upon said cutter-holder, said former having no travel relative to the work when the tool is Working, all as shown, and for the purpose' specified.

A taper and symmetrical turning box cutter for turret-lathes, combined with a long former fitted to slide in a slot in the main body and pass into the turret to obtain an extra length of Working capacity without extra length of body-piece, substantially as shown and set forth.

4. In a box-cutter for taper and symmetrical shapes, the tool-holder forced toward the Work by a former and withdrawn by the spring I1U, all substantially as shown and described.

5. A box-cutter for turning taper and symmetrical shapes on turret-lathes, consisting of a main body A, cutter-holder B, and former c, substantially as shown and described.

. JAMES HARTNESS. Witnesses:

F. C. HAMMOND, E. R. FELLoWs. 

